Promotional effect of Ag-doped Ag-V/TiO2 catalyst with low vanadium loadings for selective catalytic reduction of NOX by NH3

A series of Ag-doped Ag-V/TiO2 catalysts with low vanadium loadings were prepared by one-step sol-gel methods and the effects of the Ag doping on the selective catalytic reduction (SCR) of NOx with NH3 were investigated. The catalytic activity of the catalysts increased about 20% by the addition of 1-3 wt% of Ag. The catalysts were characterized by XRD and H-2-TPR. The results indicated that the V and Ag were well dispersed on the TiO2 support and the Ag doping inhibited the growth of TiO2 anatase crystallite and improved the oxidation ability of adsorption sites. The reduction temperature of vanadium oxide decreased and the activity for NH3-SCR enhanced. The doped Ag also had NH3-SCR activity, but it was very low. The durability of the catalysts was acceptable and the resistance to H2O was not very good. The effects of the calcination temperature and GHSV were also investigated; it was found that the optimal calcination temperature was 450 A degrees C and the GHSV should not be higher than 48,000 h(-1).